There are three types of bagworms found the North
America:
The Evergreen bagworm, the Snailcase bagworm, and the grass bagworm.
Evergreen bagworms are the most common and are found in the Eastern United
States from New England south through Texas and west to Nebraska.
The Snailcase bagworm is currently found throughout the mid Atlantic and is
making its way to the Pacific coast. Each type of bagworm creates a
specific type of bag relative to its feeding habits. Often, people will
confuse Bagworms with Tent Caterpillars.

The Bagworm is a perennial insect that gets its name from the silken bag
it constructs around itself. As a caterpillar, in the larval stage, this
insect is rarely seen. The Evergreen Bagworm and the Grass Bagworm are the
only species to produce male moths that are capable of flight. They are
black, furry, clear-winged moths that have a one inch wingspan. The adult
female remains inside her bag until she dies. Females are creamy white and
lack wings and legs.

Bagworms pass the winter as eggs inside a spindle shaped bag found on a
variety of trees and plants.
The Evergreen Bagworm prefers deciduous and evergreen trees while the Snailcase
Bagworm prefers vegetables, ornamentals, legumes, fruit and other trees.
There can be up to 1000 eggs in a single bag. The eggs hatch in mid May
and the tiny larval use silk and plant material to construct a small bag around
its hind parts. As they feed and grow, so does the bag.

Bags are made of silk and plant materials like sand, soil and
lichen. In early fall, when the bags are one to two inches big, the larvae
suspend the bags pointing downward from twigs during which time they transform
into the pupae or resting stage before becoming adults. Evergreen Bagworms
attach their bags mainly to evergreen trees making it look like pinecones.
Grass Bagworms are attached to grass until they pupate, then it attaches its bag
to the sides of fences and buildings. The Snailcase Bagworm constructs
their bags when larvae drop to the ground on silken threads and make c-shaped
cases around themselves. They are made of silk and soil particles and look
like small round pieces of dirt. This bagworm is odd because it reproduces
parthenogenetically (without males).

The Adult male Evergreen bagworm emerges in early fall when they fly in
search of females who are still in their bags. Females produce a scent or
pheromone that attracts the males to her. The male inserts his abdomen
into a hole in the bottom of the bag to mate. The female lays several
hundred eggs in a sack and then drops from her bag and dies. The eggs
remain in the bag until May when the life cycle starts all over again.
There is usually one generation per year. Adult male bagworms survive just
long enough to mate, due to underdeveloped mouthparts that prevent them from
feeding.

As young larvae, Evergreen Bagworms spin strands of silk that can be
carried by the wind to plants to feed. When disturbed, larvae will retract
back into their bag and hold the opening closed. The larvae feed on
needles and leaves and as young caterpillars, they feed on the upper parts of
plants leaving holes in the foliage. They damage orange trees in Florida
as well as junipers, spruce, pine, willow, apple, maple, elm, birch and cedar
trees across the US.
As a large population, they can cause damage by stripping plants of
foliage. Leaf damage is usually noticeable in June to late July and
August. Infestations usually go unnoticed in pine trees because the bags
look like pine cones. Some bagworms feed on specific plants while others eat a
variety of leaves from different plants.

The Snailcase Bagworm was introduced into the United States in 1940 and
discovered in Albany, New York in 1962. They are most often seen hanging from
the exterior of houses, sheds and fences. Their bags are very difficult to
get rid of and can cause damage to fences and houses when removed. The
Grass Bagworm is considered a relative cousin to the Evergreen bagworm because
it feeds on grasses and creates one-inch long silk bags that are found attached
to grass. Their bags aren't considered a nuisance.

When infestations of bagworms are detected early, control is much
easier. Once population numbers begin to multiply and spread to numerous
locations, control will require more work. If bagworm infestations are not
noticed until late summer, not only will their numbers be higher but the
bagworms will have aged enough to make them more difficult to kill with an
insecticide.

Sometimes, hand-picking of the bags or cocoons can save your trees and
shrubs.
Most have had success using a proper insecticide to spray infested trees or
shrubs, especially if treatment begins early in the season (before their numbers
are too high and the bagworms have matured into a tougher pest to kill.)

There are certain Permethrin and Acephate
products used to kill and control bagworms. However, best results have
been obtained by using Talstar One.
Talstar is a concentrated product that works at very low rates, with no odor and
a label which allows use of product on many plants, shrubs, lawns and buildings.Talstar for Trees and Shrubs Information.